My 93 (with a rebuilt 3.9) will start the first time and stays running, but if I shut it off 5 seconds or 15 minutes later, it stumbles and doesn't want to idle until I get it in gear (with the RPM a little above idle) and drive it a little. I replaced the crank sensor when I had the engne pulled and there are no codes. Sound like an AIC or bad distributor?

 

Sounds like the AIC. Take it off and see if its seazed up. Clean it up and oil it up. Try that before you spend money replacing parts.
If it was the distributer It would most likly act up with higher rpms.

 

You might also want to check the ECT and IAT sensors.